Free BMI calculator for adults and children
What is your BMI, and what does it mean for you?
Enter your age, sex, height and weight to see your BMI, category and healthy weight range.
A BMI calculator divides your weight by your height squared. For adults, a BMI of 18.5 to 24.9 is a healthy weight, 25 to 29.9 is overweight and 30 or more is obesity. For people of South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean background, overweight starts at 23 and obesity at 27.5.[1][2]
BMI at a glance
- Formula: weight (kg) ÷ height (m)², or weight (lb) × 703 ÷ height (in)².[1]
- Healthy range: 18.5 to 24.9 for most adults, and 18.5 to 22.9 with the lower cut-offs.[1][2]
- Women and men: the same adult cut-offs. Children use percentiles for their sex and age.[5]
- Waist check: keep your waist under half your height (a ratio under 0.5).[2]
- Since 2025: experts ask for a waist measure or body fat test alongside BMI before calling a high BMI excess fat.[4]
How to use the BMI calculator
- Enter your age and sex. Ages 2 to 19 get a percentile from CDC growth charts. Adults 20 and older get a BMI category.
- Enter your height and weight in US or metric units.
- Add your waist, if you can. Measure around your middle, just above your hip bones, after breathing out.
- Choose your cut-offs. Use the lower cut-offs if you have a South Asian, East Asian, Middle Eastern, Black African or African-Caribbean background.
- Read your result: BMI, category, healthy weight range, waist-to-height ratio, body roundness index and what the numbers say together.
BMI categories for adults
Adults 20 and older use fixed categories, the same for women and men. Obesity is split into three classes.[1]
| Category | Standard (WHO, CDC) | Lower (NICE, WHO Asia) |
|---|---|---|
| Underweight | Under 18.5 | Under 18.5 |
| Healthy weight | 18.5 to 24.9 | 18.5 to 22.9 |
| Overweight | 25 to 29.9 | 23 to 27.4 |
| Obesity, class 1 | 30 to 34.9 | 27.5 to 32.4 |
| Obesity, class 2 | 35 to 39.9 | 32.5 to 37.4 |
| Obesity, class 3 | 40 or more | 37.5 or more |
The lower cut-offs come from a World Health Organization expert group. It found that many Asian people face high risk of type 2 diabetes and heart disease at a BMI below 25, and proposed action points at 23, 27.5, 32.5 and 37.5.[3] The UK’s National Institute for Health and Care Excellence (NICE) uses these lower cut-offs for South Asian, Chinese, other Asian, Middle Eastern, Black African and African-Caribbean backgrounds.[2]
BMI chart by height and weight
Find your height, then the weight range for each category. BMI is rounded to one decimal, as CDC does, so the ranges meet without gaps.
| Height | Healthy weight | Overweight from | Obesity from | Healthy (lower cut-offs) | Obesity from (lower) |
|---|---|---|---|---|---|
| 4 ft 10 in | 89 to 119 lb | 120 lb | 144 lb | 89 to 109 lb | 132 lb |
| 5 ft 0 in | 95 to 127 lb | 128 lb | 154 lb | 95 to 117 lb | 141 lb |
| 5 ft 2 in | 101 to 136 lb | 137 lb | 164 lb | 101 to 125 lb | 151 lb |
| 5 ft 4 in | 108 to 145 lb | 146 lb | 175 lb | 108 to 133 lb | 160 lb |
| 5 ft 6 in | 115 to 154 lb | 155 lb | 186 lb | 115 to 142 lb | 171 lb |
| 5 ft 8 in | 122 to 164 lb | 165 lb | 197 lb | 122 to 150 lb | 181 lb |
| 5 ft 10 in | 129 to 173 lb | 174 lb | 209 lb | 129 to 159 lb | 192 lb |
| 6 ft 0 in | 137 to 183 lb | 184 lb | 221 lb | 137 to 169 lb | 203 lb |
| 6 ft 2 in | 144 to 194 lb | 195 lb | 234 lb | 144 to 178 lb | 214 lb |
| 6 ft 4 in | 152 to 204 lb | 205 lb | 247 lb | 152 to 188 lb | 226 lb |
| Height | Healthy weight | Overweight from | Obesity from | Healthy (lower cut-offs) | Obesity from (lower) |
|---|---|---|---|---|---|
| 150 cm | 41.6 to 56.1 kg | 56.2 kg | 67.4 kg | 41.6 to 51.6 kg | 61.8 kg |
| 155 cm | 44.4 to 59.9 kg | 60.0 kg | 72.0 kg | 44.4 to 55.1 kg | 66.0 kg |
| 160 cm | 47.3 to 63.8 kg | 63.9 kg | 76.7 kg | 47.3 to 58.7 kg | 70.3 kg |
| 165 cm | 50.3 to 67.9 kg | 68.0 kg | 81.6 kg | 50.3 to 62.4 kg | 74.8 kg |
| 170 cm | 53.4 to 72.1 kg | 72.2 kg | 86.6 kg | 53.4 to 66.3 kg | 79.4 kg |
| 175 cm | 56.6 to 76.4 kg | 76.5 kg | 91.8 kg | 56.6 to 70.2 kg | 84.1 kg |
| 180 cm | 59.8 to 80.8 kg | 80.9 kg | 97.1 kg | 59.8 to 74.3 kg | 89.0 kg |
| 185 cm | 63.2 to 85.3 kg | 85.4 kg | 102.6 kg | 63.2 to 78.5 kg | 94.0 kg |
| 190 cm | 66.7 to 90.0 kg | 90.1 kg | 108.2 kg | 66.7 to 82.8 kg | 99.1 kg |
How to calculate BMI
Divide weight in kilograms by height in meters, squared. In US units, multiply pounds by 703 and divide by height in inches, squared.[1]
BMI = weight (kg) ÷ height (m)²
BMI = 703 × weight (lb) ÷ height (in)²
Example: a woman who is 5 ft 5 in (65 inches) and weighs 160 lb has a BMI of 703 × 160 ÷ 4,225 = 26.6. That is overweight on both the standard and lower scales. Her healthy weight range at that height is 111 to 149 lb, or 111 to 137 lb with the lower cut-offs.
BMI Prime is BMI divided by 25, the top of the standard healthy range. Her BMI Prime is 1.07, about 7% above it.
BMI for women and men
The adult BMI categories are the same for women and men. Searches for a BMI calculator for women or for men lead to the same formula and the same cut-offs.[1]
At the same BMI, women usually carry more body fat than men, and men tend to store more of it around the waist. That is one reason the waist measurement in this calculator adds information that BMI alone cannot. The US high-risk waist line is above 35 inches (88 cm) for women and above 40 inches (102 cm) for men.[8]
BMI and age
Adult cut-offs do not change with age from 20 onward, but how to read them does after 65.[1][2]
A review of 32 studies with 197,940 adults aged 65 and older found that, compared with a BMI of 23 to 23.9, the risk of death was 12% higher at 21 to 21.9 and 19% higher at 20 to 20.9. Risk only began to rise above a BMI of about 33.[11] NICE advises reading BMI with caution in people over 65, taking into account health conditions and how well they function day to day.[2] For older adults, losing weight without trying is a reason to see a doctor.
BMI for children and teens
Ages 2 to 19 use BMI-for-age percentiles, because a healthy BMI changes as children grow. A percentile compares a child with others of the same sex and age.[5]
- Underweight: below the 5th percentile.
- Healthy weight: the 5th to under the 85th percentile.
- Overweight: the 85th to under the 95th percentile.
- Obesity: the 95th percentile or above.
- Severe obesity: 120% of the 95th percentile or more, or a BMI of 35 or more.[5]
| Age | Boys: overweight from (85th) | Boys: obesity from (95th) | Girls: overweight from (85th) | Girls: obesity from (95th) |
|---|---|---|---|---|
| 2 years | 18.1 | 19.3 | 18.0 | 19.1 |
| 4 years | 16.9 | 17.8 | 16.8 | 18.0 |
| 6 years | 17.0 | 18.4 | 17.1 | 18.8 |
| 8 years | 18.0 | 20.1 | 18.3 | 20.7 |
| 10 years | 19.4 | 22.2 | 20.0 | 23.0 |
| 12 years | 21.0 | 24.2 | 21.7 | 25.3 |
| 14 years | 22.7 | 26.0 | 23.3 | 27.3 |
| 16 years | 24.2 | 27.6 | 24.7 | 28.9 |
| 18 years | 25.7 | 29.0 | 25.7 | 30.3 |
Above the 95th percentile, CDC switched in 2022 to an extended method that spreads very high BMIs more accurately. This calculator uses it.[6][7] As a check, CDC’s own example of a 12-year-old girl who is 5 ft tall and weighs 136 lb gives a BMI of 26.6 at the 96th percentile, the obesity category. This calculator returns the same result. Always talk with your child’s doctor before changing what a child eats.
Asian BMI cut-offs
For many Asian people, health risk rises at a lower BMI, partly because more fat is stored around the waist and organs at the same weight.[3][2]
The WHO expert group noted that the BMI at which risk rises varies between Asian populations, so it did not set one cut-off for all of them. Instead it proposed action points at 23, 27.5, 32.5 and 37.5 alongside the standard scale.[3] NICE turned these into its lower cut-offs and extended them to Middle Eastern, Black African and African-Caribbean backgrounds.[2] The calculator shows your category on both scales, so you can see whether the choice changes your result.
Waist-to-height ratio
Keep your waist to less than half your height. NICE classes a ratio of 0.4 to 0.49 as healthy, 0.5 to 0.59 as increased health risk and 0.6 or more as further increased risk, for adults with a BMI under 35.[2]
| Height | Healthy waist (ratio under 0.5) | Increased risk (0.5 to 0.59) | High risk (0.6 or more) |
|---|---|---|---|
| 5 ft 0 in (152 cm) | Under 30.0 in (76 cm) | 30.0 to 35.9 in | 36.0 in (91 cm) or more |
| 5 ft 2 in (157 cm) | Under 31.0 in (79 cm) | 31.0 to 37.1 in | 37.2 in (94 cm) or more |
| 5 ft 4 in (163 cm) | Under 32.0 in (81 cm) | 32.0 to 38.3 in | 38.4 in (98 cm) or more |
| 5 ft 6 in (168 cm) | Under 33.0 in (84 cm) | 33.0 to 39.5 in | 39.6 in (101 cm) or more |
| 5 ft 8 in (173 cm) | Under 34.0 in (86 cm) | 34.0 to 40.7 in | 40.8 in (104 cm) or more |
| 5 ft 10 in (178 cm) | Under 35.0 in (89 cm) | 35.0 to 41.9 in | 42.0 in (107 cm) or more |
| 6 ft 0 in (183 cm) | Under 36.0 in (91 cm) | 36.0 to 43.1 in | 43.2 in (110 cm) or more |
| 6 ft 2 in (188 cm) | Under 37.0 in (94 cm) | 37.0 to 44.3 in | 44.4 in (113 cm) or more |
The ratio works the same for women and men and for all ethnicities, and NICE says it can also be used in people with a lot of muscle.[2] To measure, find the bottom of your ribs and the top of your hips, and wrap the tape around the middle point after breathing out.
Body roundness index
Body roundness index (BRI) uses waist and height to estimate how round the body is. It was built to predict total and visceral fat a little better than BMI or waist alone.[9]
BRI = 364.2 − 365.5 × √(1 − (waist ÷ 2π)² ÷ (0.5 × height)²)
| Body roundness index | Risk of death compared with 4.5 to 5.5 |
|---|---|
| Under 3.4 | 25% higher |
| 4.5 to 5.5 | Reference (lowest) |
| 6.9 or more | 49% higher |
In the US study, BRI rose steadily over 20 years of national surveys.[10] The researchers called for more studies before BRI is used in practice, so treat it as an extra view, not a verdict. For the example woman with a 34 inch waist, BRI is 3.8 and her waist-to-height ratio is 0.52.
What changed in 2025: BMI is a screening number
A Lancet Commission of 58 experts said BMI alone should not be used to diagnose obesity. Excess body fat should be confirmed with at least one waist measure, such as waist-to-height ratio, or a direct body fat test. At a BMI above 40, excess fat can be assumed.[4]
The Commission also separated excess body fat that is not yet harming health from excess fat that is already affecting organs or daily life. Telling them apart needs a doctor’s assessment.[4] That is why this calculator asks for your waist and explains what your BMI and waist say together, rather than giving one label.
What BMI cannot tell you
- Muscle versus fat. Very muscular people can have a high BMI with little fat. NICE advises caution in this group.[2]
- Where fat sits. Fat around the middle carries more risk than fat on the hips. A waist measure fills this gap.[8]
- Pregnancy. BMI is not used to judge weight during pregnancy.
- Your health. Blood pressure, blood sugar, cholesterol, fitness and sleep matter as much as any body measure.
What to do with your result
If your BMI and waist are in the healthy range, keep doing what works: whole foods, daily movement and good sleep. If either is high, small steady changes are more likely to last than strict diets. The calorie calculator estimates how much energy you need, and the nutrition calculator shows what is in your meals. Walking is the easiest place to start; the steps to calories calculator turns your steps into miles and calories.
BMI is one number. For a wider view of health, try the VO2 max calculator for fitness and the biological age calculator, which scores everyday habits. For meals that support a healthy weight, see the healthy diet basics. In Ayurveda, body frame differs by dosha; the free dosha quiz shows which dosha leads for you.
More free tools for daily health decisions.
BMI calculator FAQ
What is a healthy BMI for adults?
For most adults, a BMI of 18.5 to 24.9 is the healthy weight range. 25 to 29.9 is overweight and 30 or more is obesity. For people of South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean background, NICE uses lower cut-offs: overweight from 23 and obesity from 27.5.
How do you calculate BMI?
Divide your weight in kilograms by your height in meters squared. In US units, multiply your weight in pounds by 703, then divide by your height in inches squared. For example, 160 lb at 5 ft 5 in (65 in) gives 160 x 703 / 4,225 = 26.6.
Is BMI different for women and men?
No. Adults use the same BMI cut-offs whatever their sex. At the same BMI, women usually carry more body fat than men, which is one reason a waist measurement adds useful information. For children and teens, BMI is compared with charts for their sex and age.
Does a healthy BMI change with age?
The adult cut-offs are the same from age 20 onward. For adults 65 and older, a review of 32 studies found that the risk of death was not raised across a BMI of about 23 to 33, but was 12% to 19% higher at 20 to 22. NICE advises reading BMI with caution after 65.
What is the Asian BMI cut-off?
A WHO expert group found that many Asian people face higher risk of type 2 diabetes and heart disease below a BMI of 25. It proposed action points at 23, 27.5, 32.5 and 37.5. NICE uses 23 for overweight and 27.5 for obesity for South Asian, Chinese, other Asian, Middle Eastern, Black African and African-Caribbean backgrounds.
Is BMI accurate?
BMI is a good screening tool for groups, but it cannot tell muscle from fat or show where fat sits. In 2025, a Lancet Commission of 58 experts said high BMI should be confirmed with a waist measurement, such as waist-to-height ratio, or a direct body fat test, except at a BMI above 40.
What is a healthy waist-to-height ratio?
Under 0.5. NICE classes 0.4 to 0.49 as healthy, 0.5 to 0.59 as increased health risk and 0.6 or more as further increased risk, for adults with a BMI under 35. The short message is to keep your waist to less than half your height.
What is the body roundness index?
The body roundness index (BRI) uses waist and height to estimate body shape. In 32,995 US adults, risk of death was lowest in the middle range of 4.5 to 5.5. It was 25% higher below 3.4 and 49% higher at 6.9 or more. It is a research measure, not yet a clinical standard.
How is BMI worked out for children?
Children and teens 2 to 19 use BMI-for-age percentiles from CDC growth charts. Below the 5th percentile is underweight, the 5th to under the 85th is a healthy weight, the 85th to under the 95th is overweight, and the 95th or above is obesity. Severe obesity starts at 120% of the 95th percentile or a BMI of 35.
What BMI counts as obesity?
A BMI of 30 or more for most adults, divided into class 1 (30 to 34.9), class 2 (35 to 39.9) and class 3 (40 or more). With the lower cut-offs, obesity starts at 27.5, and classes 2 and 3 start at 32.5 and 37.5.
What is BMI Prime?
BMI Prime is your BMI divided by 25, the top of the standard healthy range. A BMI Prime of 1.0 is at the top of the range, below 1.0 is under it and 1.2 means 20% above it.
Does muscle affect BMI?
Yes. Muscle is denser than fat, so very muscular people can have a high BMI with little body fat. NICE advises reading BMI with caution in people with high muscle mass. A healthy waist-to-height ratio alongside a high BMI often points to muscle rather than fat.
Is 140 lb overweight for 5 ft 4 in?
At 5 ft 4 in, 140 lb gives a BMI of 24.0, which is inside the standard healthy range of 18.5 to 24.9. Under the NICE cut-offs for people of South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean background, overweight starts at 23, so the same result would count as overweight. A waist measure adds useful context.
How much should a 5 ft 5 in woman weigh?
For an adult who is 5 ft 5 in, the healthy BMI range of 18.5 to 24.9 works out to about 111 to 149 lb. The range is the same for women and men. With the NICE cut-off of 23 for some ethnic groups, the top of the range is about 137 lb. Muscle, frame and age all change what is right for one person.
Is a BMI of 25 really overweight?
By the CDC and WHO definitions, yes: a BMI of 25 to 29.9 is classed as overweight. It is a screening category, not a diagnosis. A 2025 Lancet Commission said BMI alone should not be used to diagnose obesity, and that excess body fat should be confirmed with a waist measure or a direct body fat test.
Do doctors still use BMI?
Yes, as a first screening step. The CDC still uses BMI categories for adults, and NICE pairs BMI with waist-to-height ratio. The 2025 Lancet Commission on clinical obesity kept BMI for screening but said it should be confirmed with other measures before anyone is diagnosed with obesity.
Sources
- Centers for Disease Control and Prevention. Adult BMI categories. 2024. cdc.gov/bmi/adult-calculator/bmi-categories.html
- National Institute for Health and Care Excellence. Overweight and obesity management (NG246): identifying and assessing overweight, obesity and central adiposity. 2025. nice.org.uk/guidance/ng246/chapter/identifying-and-assessing-overweight-obesity-and-central-adiposity
- WHO Expert Consultation. Appropriate body-mass index for Asian populations and its implications for policy and intervention strategies. Lancet. 2004;363:157-163. pubmed.ncbi.nlm.nih.gov/14726171
- Rubino F, et al. Definition and diagnostic criteria of clinical obesity. Lancet Diabetes Endocrinol. 2025;13(3):221-262. pubmed.ncbi.nlm.nih.gov/39824205
- Centers for Disease Control and Prevention. Child and teen BMI categories. 2024. cdc.gov/bmi/child-teen-calculator/bmi-categories.html
- Centers for Disease Control and Prevention. Data files for the extended CDC BMI-for-age growth charts. 2022. cdc.gov/growthcharts/extended-bmi-data-files.htm
- Wei R, Ogden CL, Parsons VL, Freedman DS, Hales CM. A method for calculating BMI z-scores and percentiles above the 95th percentile of the CDC growth charts. Ann Hum Biol. 2020;47(6):514-521. pubmed.ncbi.nlm.nih.gov/32901504
- National Heart, Lung, and Blood Institute. Assessing your weight and health risk (waist circumference). nhlbi.nih.gov/health/educational/lose_wt/risk.htm
- Thomas DM, et al. Relationships between body roundness with body fat and visceral adipose tissue emerging from a new geometrical model. Obesity. 2013;21(11):2264-2271. pubmed.ncbi.nlm.nih.gov/23519954
- Zhang X, et al. Body roundness index and all-cause mortality among US adults. JAMA Netw Open. 2024;7(6):e2415051. pubmed.ncbi.nlm.nih.gov/38837158
- Winter JE, MacInnis RJ, Wattanapenpaiboon N, Nowson CA. BMI and all-cause mortality in older adults: a meta-analysis. Am J Clin Nutr. 2014;99(4):875-890. pubmed.ncbi.nlm.nih.gov/24452240
This BMI calculator is for general education. BMI is a screening number, not a diagnosis, and it does not measure body fat directly. For children, pregnant people, athletes and adults with a health condition, talk with a doctor or registered dietitian about your result. Reviewed by Dr. Goutom Banik, MBBS, MPH.
